It is well known that such measuring devices are highly sensitive to waves of the fuel in the tank, due to the shape of the road or to accelerations and decelerations of the vehicle.
Attempts have been made to limit the effect of waves of fuel by associating a damping device with the moving equipment so as to smooth the information delivered by the rheostat type sensitive member.
As already described in patent applications numbers FR-A No. 838 289, 2 306 433, and DE-A Nos. 1 228 814, 1 269 815, proposals have been made for damping devices comprising a closed cylindrical chamber containing a moving piston, with the chamber and the piston being connected to different elements of the moving equipment. These damping devices behave like a hydraulic shock absorber, with the hydraulic fluid of the shock absorber for braking displacement of the piston being constituted, in this case, by the fuel in the tank.
Proposals have also been made, as described in German patent specification DE-B No. 1 155 262 to provide a damping device comprising a housing defining a sealed chamber containing a viscous damping fluid, such as silicone, and receiving a blade capable of relative displacement within the housing. The blade is received in the housing and is connected to the moving equipment. The displacements of the blade in the chamber filled with viscous fluid, and consequently the displacements of the moving equipment, are braked by the controlled flow of fluid from one side of the blade to the other via interstices between the blades and the housing.
Similarly, in the above-mentioned piston-and-chamber damping devices the damping and braking effect is due to the controlled flow of fluid from one side of the piston to the other side thereof via interstices between the piston and the cylinder chamber.
The aim of the present invention is to provide a new damping device which provides an improved damping effect over prior art damping devices.
Another aim of the present invention is to provide a damping device which is simple in structure and is therefore easily mass produced, and which also has a completely uniform response, i.e. a completely uniform damping coefficient.
Another aim of the present invention is to provide a damping device which is very strong and reliable.
Another aim of the present invention is to provide a damping device capable of withstanding large changes in temperature without being damaged.
Another aim of the present invention is to provide a damping device which is completely sealed so as to avoid polluting its environment, i.e. a damping device from which it is impossible for any viscous fluid, in particular silicone, to leak out into the fuel tank, and which is also completely insensitive to fuel vapors.